It is all housed in a custom cardboard/papier mache housing with attached grip.
You will need:
An Arduino, I used an Arduino UNO.
Ultrasonic range sensor - I used an HC-SR04, generic from ebay
Piezo speaker or buzzer for sound.
Bunch of LEDs in red and white.
Bunch of resistors to prevent your LEDs from burning out. Use any online LED calculator to figure out the value of the resistor needed based on the specs of your circuit.
A couple of tactile switches and a slide switch for the battery pack.
A battery pack to make it portable.
Wire for the electronics
Cardboard and glue
Something to cover the front, plexiglas, acrylic, or I used some scrap window screen metal mesh.
CAUTION: Crafting is hazardous, pointy things and sharp things are pointy and sharp. Know how to solder and use electronics safely.